6 
GARDENING IN THE SOUTHWEST 
See Tiny 
Squares on 
Soil Map 
Symbols c 
Soil Map 
Combine 
differentiation being mostly in the shifting extremes in tempera¬ 
ture every twenty-four hours. 
CALCAREOUS 
The calcareous, or disintegrated limestone, soils of the central 
section of the Southwest, have had very little written about them. 
They are extremely rich, having supported a series of crops year 
after year for many years, without the need of fertilization nor 
any reduction in productiveness. 
Being “derived through the disintegration of the underlying 
beds of highly calcareous rocks, these strata contain much lime 
carbonate. (P. 1323)*. The accumulation of decayed vegetable- 
matter under the prevailing humid conditions and in the pres¬ 
ence of lime carbonate has caused the surface soil of the greater 
part of these prairie lands to have a decidedly dark or black color. 
This type is locally called 'black, waxy land’.” (P. 1227.)* 
Often “large (P. 1227)* deep cracks form in this soil in very 
dry weather. ,, Another “characteristic is, this soil will crumble 
down on drying to a mass of small aggregates . . . Even clods 
turned up when wet crumble at the first rain and assume a desir¬ 
able tilth. Extending (P. 1231)* back from the stream valleys the 
depth of the soil increases and the quantity of rock fragments on 
the surface decreases. The surface soil of many acres is strewn 
with fragments of the parent rock.” These “weather rapidly into 
soil.” This soil varies in productivity according to the depth of 
material over the basic chalk or limestone rock.”* Being more or 
less clayey in texture, the addition of humus, leaf-mold and sand is 
necessary to render it more friable under all conditions. It will then 
grow any type of plant except those demanding a high degree 
of acidity (see page 53). 
A. Central Oklahoma contains black, heavy soil, calcareous 
in the main and yet not as rich nor as deep as the “black-waxy” 
lands. The chief deficiency of this soil is phosphorus. Sudden varia¬ 
tions in temperature in winter, coupled with the hot winds of sum¬ 
mer, are the chief problems to be met to secure successful garden- 
* "Soil Survey’’—Texas A. & M.—William Carter—1924. 
